Wind tracking system of a wind turbine

Abstract

The present patent application concerns a wind turbine comprising a hub and at least one rotor blade connected to the hub, the hub and the at least one rotor blade forming a wind rotor that is rotatable about a rotor axis that converts kinetic energy of the wind into another form of energy and rotatable about a yaw axis that changes the yaw of the rotor, the wind turbine further comprising at least one sensing device that senses a yaw moment of the wind rotor and the wind turbine being adapted to control the yaw of the wind rotor depending on a signal of the sensor.

1 . A wind turbine comprising a hub and at least one rotor blade connected to the hub, the hub and the at least one rotor blade forming a wind rotor that is rotatable about a rotor axis for converting kinetic energy of the wind into another form of energy and rotatable about a yaw axis for changing the yaw of the wind rotor, the wind turbine further comprising at least one sensing device that senses a yaw moment of the wind rotor and the wind turbine being adapted to control the yaw of the wind rotor depending on a signal of the sensor. 
     
     
         2 . The wind turbine according to  claim 1 , wherein wind turbine comprises a tower, the wind rotor being arranged on the tower, wherein the sensor is adapted to sense a bending moment of the tower. 
     
     
         3 . The wind turbine according to  claim 1 , wherein the yaw axis is substantially vertical. 
     
     
         4 . The wind turbine according to  claim 1 , wherein the rotor axis is substantially horizontal. 
     
     
         5 . The wind turbine according to  claim 1 , wherein the wind turbine comprise a rotor shaft, the wind rotor being connected to the rotor shaft for rotating the rotor shaft about the rotor axis, wherein the sensor is adapted to sense a bending moment of the rotor shaft in yaw direction. 
     
     
         6 . The wind turbine according to  claim 1 , wherein the wind turbine comprise a yaw drive for rotating the wind rotor about the yaw axis, wherein the sensing device is adapted to sense the torque imparted by the rotor on the yaw drive. 
     
     
         7 . The wind turbine according to  claim 6 , wherein the yaw drive is an electric motor. 
     
     
         8 . The wind turbine according to  claim 7 , wherein the sensing device is an ammeter measuring the armature current of the motor. 
     
     
         9 . A controller for a wind turbine comprising a hub and at least one rotor blade connected to the hub, the hub and the at least one rotor blade forming a wind rotor that is rotatable about a rotor axis for converting kinetic energy of the wind into another form of energy, the wind rotor being rotatable about a yaw axis for changing the yaw of the wind rotor, and the controller being adapted to control a yaw depending on a signal of a sensing device sensing a yaw moment of the wind rotor. 
     
     
         10 . The controller according to  claim 9 , further comprising a low pass filter adapted to filter the signal of the sensing device. 
     
     
         11 . The controller according to  claim 9 , wherein the low pass filter has a cutoff frequency of less than about 8.3×10 −3  Hz. 
     
     
         12 . The controller according to  claim 10 , further adapted to change the yaw of the wind rotor if the filtered yaw moment exceeds a predetermined value. 
     
     
         13 . The controller according to  claim 9 , wherein the controller is a PID or PI controller. 
     
     
         14 . A method that controls a yaw angle of a wind turbine, the wind turbine comprising a hub and at least one rotor blade connected to the hub, the hub and the at least one rotor blade forming a wind rotor that is rotatable about a rotor axis that converts kinetic energy of the wind into another form of energy, the wind rotor being rotatable about a yaw axis that changes the yaw of the wind rotor, the method comprising:
 Sensing a yaw moment; and   Controlling the yaw depending on the yaw moment.   
     
     
         15 . The method according to  claim 14 , wherein the sensed values of the yawing moment is low pass filtered. 
     
     
         16 . The method according to  claim 14 , wherein the sensed values of the yawing moment is low pass filtered with a cutoff frequency of less than 8.3×10 −3  Hz. 
     
     
         17 . The method according to  claim 14 , wherein the sensed value is checked for plausibility. 
     
     
         18 . The method according to  claim 14 , wherein the yaw of the wind rotor is controlled by a proportional control, a proportional-integral control or look-up table control method using the yaw moment as an input value. 
     
     
         19 . The method according to  claim 18 , wherein a setpoint value is a yaw moment or a yaw angle equal to zero. 
     
     
         20 . The method according to  claim 15 , wherein the yaw of the rotor is changed if the filtered yaw moment exceeds a predetermined value. 
     
     
         21 . A wind turbine comprising:
 a sensor;   a blade connected to a hub;   a rotor shaft rotating about a rotor axis; and   the sensor adapted to sense a bending moment of the rotor shaft in a yaw direction, and a control to output a signal to control at least one operational parameter of the wind turbine.